Miter saw

ABSTRACT

In accordance with the present invention, an improved miter saw is employed. The miter saw includes a base assembly, a rotatable table rotatably connected to the base assembly, the table having a table plane, a fence connected to the base assembly and having a fence plane, a saw assembly including a motor and a blade driven by the motor, the blade having a radius and a blade center, and a pivot arm pivotally attached to the table and pivotally supporting the saw assembly about a first axis substantially parallel to the table plane, allowing a user to plunge the blade below the table plane, wherein the distance between the first axis and the table plane is about 0.472 times the radius. Also, the distance between the first axis and the fence plane is about 1.45 times the radius, and the distance between the first axis and the blade center is about 1.882 times the radius. In addition, the distance between the blade center and the table plane is about 0.57 times the radius when the blade is plunged below the table plane.

FIELD OF THE INVENTION

This invention relates generally to miter saws.

BACKGROUND OF THE INVENTION

A typical miter saw has a base assembly, including a rotatable tablerotatably connected to the base assembly, a saw assembly including amotor and a blade driven by the motor, a pivot arm pivotally attached tothe base assembly and supporting the saw assembly, allowing a user tomove the saw assembly towards and away from the base assembly forcutting a workpiece. A miter saw can be used for cutting crown molding,wood beams, etc.

Typically, the cutting capacity of a miter saw is limited because of itsblade size and/or geometry. For example, most currently availableten-inch non-sliding miter saws can cut nominal 4″ by 4″ and 2″ by 6″wood beams. However, these miter saws cannot cut some of the largerboards, which are about six inches wide, true size. Accordingly, if auser wants to cut a board that is larger than the cutting capacity ofthe miter saw, the user would need to purchase a larger miter saw, witha larger blade, higher weight, higher price, etc. Alternatively, theuser could use a radial arm saw or sliding miter saw. But these are alsomore expensive, etc.

SUMMARY OF THE INVENTION

In accordance with the present invention, an improved miter saw isemployed. The miter saw includes a base assembly, a rotatable tablerotatably connected to the base assembly and having a plane, a sawassembly including a motor and a blade driven by the motor, and a pivotarm pivotally attached to the table and supporting the saw assembly,allowing a user to plunge the blade below the table plane, wherein thearea of the blade below the table plane is between about 14.4% and about50% of the blade area.

Additional features and benefits of the present invention are described,and will be apparent from, the accompanying drawings and the detaileddescription below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of theinvention according to the practical application of the principlesthereof, and in which:

FIG. 1 is a perspective view of a miter saw according to the presentinvention;

FIG. 2 is a front view of the miter saw;

FIG. 3 is a top plan view of the miter saw along line III-III of FIG. 2;

FIG. 4 is a left side view of the miter saw;

FIG. 5 is a right side view of the miter saw;

FIG. 6 is a right side view of the miter saw in a beveled position; and

FIG. 7 shows part of a stop mechanism for use with the miter saw.

DETAILED DESCRIPTION

The invention is now described with reference to the accompanyingfigures, wherein like numerals designate like parts. Referring to FIGS.1-5, a miter saw 10 has a base assembly 11. Base assembly 11 preferablyincludes a rotatable table 12 rotatably connected to the base assembly11, which allows a user to change the saw blade miter angle as is wellknown in the art.

In addition, the miter saw 10 has a saw assembly 30 including a motor 17(shown in broken lines) and a blade 14 driven by the motor 17.Preferably saw assembly 30 is pivotally connected to base assembly 11(and/or table 12) via arm 8 to allow the user to move the blade 14towards table 12 in a chopping action. Arm 8 may be connected to pivotjoint 19 which allows the saw assembly 30 be pivoted about axis A, so asto pivot saw assembly 30 downwardly for cutting a workpiece, and/orabout bevel axis B, so as to change the bevel angle between the blade 14and the plane of base assembly 11 and/or table 12.

Preferably, the motor 17 is covered by housing 16. A handle 18 may beconnected to the housing 16. Handle 18 preferably has a first horizontalhandle 18H for enabling a user to pivot the saw assembly 30 downwardly.In addition, handle 18 may have a second horizontal handle 18Csubstantially perpendicular to the first handle 18H for enabling a userto carry the miter saw 10.

A sliding fence assembly 20 may be disposed on the left side of mitersaw 10. Preferably fence assembly 20 is disposed on the left side 11L ofbase assembly 11. Persons skilled in the art are referred to U.S. Pat.No. 5,297,463, entitled “Adjustable fence for compound miter saw”, whichis hereby incorporated in whole by reference.

A fence 21 may also be disposed on the right side of miter saw.Preferably fence 21 is disposed on the right side 11R of base assembly11. Preferably fence 21 is coplanar with fence assembly 20.

As mentioned above, the saw assembly 30 is pivotable about an axis A.The distance between the axis A and the plane 11P of the base assembly11 and/or table 12 is distance ABP. Preferably the distance ABP is about0.472 times the radius R of blade 14. In a ten-inch miter saw having ablade of about 5 inches radius, the distance ABP is about 2.36 inches.Similarly, the distance between the axis A and the plane 20P is distanceAFP. Preferably the distance AFP is about 1.45 times the radius R.Accordingly, in a ten-inch miter saw, the distance AFP is about 7.25inches.

Furthermore, it is preferable that the distance between axis A and bladecenter BC, i.e., distance ABC, is about 1.882 times the radius R.Accordingly, in a ten-inch miter saw, the distance ABC is about 9.41inches.

It is also preferable that, during the chopping operation, the bladecenter BC reaches a point where the distance between the blade center BCand the plane 11P, i.e., distance BCBP, is about 0.57 times the radiusR, or, in a ten-inch miter saw, about 2.85 inches.

Persons skilled in the art will note that such arrangement requires asubstantial portion 14U of blade 14 to be plunged below plane 11P. It ispreferable that the area of portion 14U is between about 14.4% and about50% of the total blade area, and most preferably is at least about15.75% of the total area. Accordingly, for a ten-inch blade having anarea of about 50,670.75 squared millimeters (the areas of the arbor holeor of the space between blade teeth have not been subtracted), the areaof portion 14U should be between about 7,296.60 squared millimeters andabout 25,335.37 squared millimeters (the area of the spaces betweenblade teeth has not been subtracted). Preferably, the area of portion14U is at least about 7,984 squared millimeters.

Persons skilled in the art will recognize that, with such arrangement,the table plane 11P intersects blade 14, forming a chord CA. The lengthof this chord CA may be at least 1.6 times the radius R. Preferably thelength of chord CA is at least about 1.642 times the radius R, i.e., atleast about 8.21 inches for a ten-inch blade. This chord length wouldconstitute the cutting capacity, but for the placement of fences 20, 21.Accordingly, the cutting capacity would be the distance between thefront endpoint of chord CA and the fence plane 20P, i.e., distance CC.Preferably, distance CC is at least 1.1 times the radius R. It ispreferable that distance CC is at least about 1.236-1.252 times theradius R, or at least about 6.18-6.26 inches for a ten-inch blade.Preferably, distance CC is about 1.244 times the radius R, or about 6.22inches for a ten-inch blade. It is also preferable that the ratiobetween distance CC and the length of chord CA is between about 0.60 andabout 0.775, and preferably about 0.757.

With such arrangement, a ten-inch miter saw will be able to cut throughnominal 4″ by 4″ and 2″ by 6″ wood beams, like most currently availableten-inch non-sliding miter saws. In addition, a ten-inch miter sawhaving such arrangement will be able to cut through boards that is 6inches wide (true size) at 0° miter angle, and/or 5.25 inches wide at31.62° miter angle, unlike any available ten-inch non-sliding mitersaws.

Referring to FIGS. 2-3 and 5, the motor housing 16 intersects the plane20P when the saw assembly 30 is at the lowest chopping position and at a0° miter and bevel angles. (Persons skilled in the art will recognizethat such result may occur because of the arrangement discussed above.)In order to avoid contact between the motor housing 16 and fence 21, atleast part of the fence 21 located underneath housing 16 is disposedwith a height H′, which is lower than the motor housing 16. It is alsopreferable to provide at least one portion 21E of fence 21 at height H,which is preferably higher than the housing 16, for better support of ataller workpiece. Accordingly, such portion 21E could be provided to theright of housing 16.

Such arrangement could result in a right fence 21 longer than the rightfences found in most typical miter saws. According to typical miter sawdesign principles, the distance between the end of fence 21 and the kerfline 12K, i.e., the line defined by the intersection of plane 11P andblade 14, is about equal to the distance between the kerf line 12K andthe end of the right side 11R, i.e., distance KRS. Similarly, thedistance between the end of fence 20 and the kerf line 12K is aboutequal to the distance between the kerf line 12K and the end of left side11L, i.e., distance KLS. Persons skilled in the art will recognize thatthis last principle is usually maintained in miters saws having slidingfence assemblies when the sliding fence is slid to the position closestto blade 14.

Furthermore, distance KLS is typically equal to distance KRS. Similarly,the distance between the end of fence 21 and the kerf line 12K istypically equal to the distance between the end of fence 20 and the kerfline 12K. Again, persons skilled in the art should recognize that thisprinciple is typically maintained in a miter saw with a sliding fenceassembly when the sliding fence is slid to the position closest to blade14.

Accordingly, if the prior art design principles are followed, the leftside 11L and/or fence 20 will be longer, because of the longer length offence 21 and/or right side 11R. This however results in a larger,heavier base. Thus it is preferable to provide a base assembly 11 wherethe distance KRS is larger than the distance KLS. Similarly, it ispreferable that the distance between the end of fence 21 and the kerfline 12K be larger than the distance between the end of fence 20 and thekerf line 12K. If the miter saw is provided with a sliding fenceassembly, the distance between the end of fence 21 and the kerf line 12Kmay be larger than the distance between the end of fence 20 and the kerfline 12K, when the fence 20 is slid to the position closest to blade 14.In other words, the ratio between distances KRS and KLS is preferablylarger than 1:1, and should be at least about 1.06:1. For a ten-inchmiter saw built accordingly, the distances KRS and KLS may be about 267millimeters and 251 millimeters, respectively.

Another aspect of the invention is shown in FIGS. 3-7. Preferably, mitersaw 10 is provided with a stop mechanism 50. Stop mechanism 50 maycomprise a movable stop 53 attached to saw assembly 30, and preferablyattached to arm 8. In addition, stop mechanism 50 may include a fixedstop 51 disposed on base assembly 11, and preferably on table 12. As sawassembly 30 is pivoted in a chopping action, movable stop 53 contactsfixed stop 51, limiting any further pivoting of saw assembly 30.

Fixed stop 51 has a surface 51S for contacting movable stop 53.Preferably, surface 51S can be “programmed” so as to vary the choppingmotion range for the saw assembly 30 at different bevel angles. Forexample, it may be desirable to provide the full chopping motion rangewhen the saw assembly 30 is at a 0° bevel angle (as shown in FIG. 5),whereas the chopping motion range may be limited when the saw assembly30 is at a 45° bevel angle. Persons skilled in the art will recognizethat such result may be desirable in order to avoid contact betweenfence 20 and lower blade guard 15 when the saw assembly 30 is pivoteddownwardly at a 45° bevel angle. Alternatively, such result may bedesired in order to obtain a smaller cutting capacity CC′. Accordingly,fixed stop 51 can be programmed to obtain such result by providing anappropriate surface 51S, such as that shown in FIG. 7.

Persons skilled in the art will recognize that surface 51S may beprogrammed to obtain different results. For example, surface 51S may beprogrammed to limit the chopping motion range at other bevel positionsin order to increase the height of fence 20.

Persons skilled in the art may recognize other alternatives to the meansdisclosed herein. However, all these additions and/or alterations areconsidered to be equivalents of the present invention.

1. A miter saw comprising: a base assembly; a nonremovable fenceattached to the base assembly for supporting a workpiece: a rotatabletable rotatably connected to the base assembly, the table having a planefor supporting the workpiece; a saw assembly including a motor and ablade driven by the motor; and a pivot arm pivotally attached to thetable and supporting the saw assembly, allowing a user to plunge theblade below the table plane; wherein area of the blade below the tableplane when plunged is between about 14.4% and about 17.5% of total bladearea.
 2. The miter saw of claim 1, wherein the blade area below thetable plane is about 15.75% of the total blade area.
 3. The miter saw ofclaim 1, further comprising a sliding fence connected to the baseassembly. 4-11. (canceled)